Existing power generation methods typically fall into specific groups, namely: (1) baseload power delivery, which comes from generators that have technologies that enable them to economically sign contracts to sell power 24 hours a day, seven days a week, such as nuclear, coal, hydro, biomass, and some combined cycle gas; (2) intermediate power delivery, which is power delivered approximately 16 hours a day, either 5 or 7 days a week, mainly from combined cycle gas plants; (3) peaker power delivery, which is delivery of power for about eight hours a day, 5 days a week, and is roughly coincident with peak load, and which is mainly from simple and combined cycle gas plants and some diesel plants; and (4) intermittent sources which cannot be scheduled, such as wind and solar. In addition to these power generation services, there are also markets for power quality services, such as frequency regulation up, frequency regulation down, capacity, black start, ramp-rate control, spinning reserve, and non-spinning reserve.
Current technologies that are directed toward renewable energy sources mainly transform intermittent resources such as wave, wind and solar into intermittent power. Many of these renewable resources are difficult to predict and schedule. The extensive development of global wind-power has given rise to efforts to address the challenges of intermittent energy sources with respect to generating electricity for power grids. Many of these efforts involve the development of means to condition intermittent electric power sources that supply a grid, so as to minimize or counteract the disturbances that would otherwise affect the grid in undesirable ways. Other efforts involve developing energy storage means that can act to the benefit of wind farms and other intermittent sources of renewable energy. Energy storage means provide a benefit for intermittent sources by harvesting into storage so-called excess capacity during periods when electricity may be generated in excess of the current electricity demand. The electricity that might be generated, for example, by a wind farm during periods when wind energy exceeds the grid's energy consumption, might be assigned a low or negative price, or the wind farm curtailed (disconnected) from supplying energy to the grid. Similarly, in a grid significantly powered by intermittent sources, grid energy demand might go unmet during periods when energy demand is greater than the available wind energy.
One important form of power conditioning that may facilitate increased use of wind, and similarly intermittent renewable energy sources, is the development of means to transform wind energy from being an intermittent power resource to being a fully dispatchable power resource able to offer firm power contracts. Firm power contracts are contracts to deliver a specified amount of energy to a specified point during a specified time period, and require the seller to pay penalties if they cannot meet the terms of the contracts. Firm contracts command a price premium to intermittent contracts in most markets, and are therefore valuable. Efforts to transform intermittent wind into firm power have heretofore depended upon forecasting future wind velocities (for purposes of selling into the day-ahead market), and coordinating operation of the wind-power generation with other remotely sited intermittent power sources, and/or coordination with more-constant power sources, such as hydro, whose power flow rate can be varied up or down to compensate for higher or lower flow rate from a wind farm, and/or coordination with thermal generators such as simple cycle gas plants and diesel plants that can ramp up or down in response to the real-time output of wind farms. Such coordination efforts do not transform intermittent wind energy into firm power, but they do help intermittent wind to be integrated into the grid. Power generators must increasingly participate in competitive markets established to govern electric power generation/sale/trading. Therefore, the development of wind (and other intermittent renewable energy sources) in the United States (and other parts of the world) is severely impeded by its lower market value.
A means to enhance the economic value of wind and other intermittent renewable energy sources in the competitive deregulated power trading market is vital to increasing deployment of renewable energy generation. Increasing the economic value of wind is perhaps the most important long-range determinative factor for renewable energy growth in the United States. Given a federal commitment to maintain and develop competitive markets for electric power generation/sale/trading, the self-evident competitive drivers for use of renewable energy are enhanced price and reduced cost. Governmental and academic studies of the future prospects for renewable energy explicitly recognize the significance of price and cost factors in the current day competitive market.
To date, various efforts to provide energy storage to wind farms have not transformed wind-generated electric power into firm power within the pricing framework of the grid, even though the addition of storage has ameliorated to some extent the intermittent nature of wind-power. Implementations of compressed air energy storage (CAES), pumped hydro storage, battery, flywheel, thermal storage, and other storage means have been limited in this regard by technology. Existing technology has not demonstrated the ability to produce electric power outputs that are valued by the competitive grid as premium power.
Accordingly, there exists a need to provide systems and methods that transform intermittent power into firm power, such that the use of renewable energy sources is further encouraged.